CVE-2026-91786 in Red Hat
Summary
by MITRE • 09/15/2026
A flaw was found in GNOME Shell. When processing icons from a remote search provider via D-Bus, the system fails to validate the icon's declared dimensions against the actual data buffer size. A malicious or compromised remote search provider could exploit this by providing oversized icon dimensions, leading to an out-of-bounds read. This can cause the GNOME Shell process to crash, disrupting the user's session, and potentially disclose sensitive information from adjacent memory.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 09/15/2026
The vulnerability identified in GNOME Shell represents a critical failure in input validation during the processing of remote search provider data via the D-Bus messaging system. Specifically, when handling icon metadata retrieved from external sources, the application fails to verify that the declared dimensions of an image align with the actual size of the underlying data buffer. This lack of boundary checking creates a classic out-of-bounds read condition, where the software attempts to access memory locations beyond the allocated limits of the buffer based on incorrect dimension parameters provided by the remote service.
From a technical perspective, this flaw is categorized under CWE-125, which describes Out-of-Bounds Read vulnerabilities. The root cause lies in the absence of rigorous sanity checks before parsing or rendering icon data received over D-Bus connections. In typical operation, GNOME Shell relies on these icons to populate search results and application menus efficiently. However, when a malicious or compromised remote search provider supplies an icon definition with dimensions that exceed the actual byte length of the image data, the shell's renderer proceeds to read past the end of the buffer. This behavior violates fundamental memory safety principles expected in desktop environment components that handle untrusted input from networked services.
The operational impact of this vulnerability is significant for system stability and potential information disclosure. The immediate consequence is a denial of service, as the out-of-bounds read typically triggers an access violation or segmentation fault within the GNOME Shell process. This results in the abrupt termination of the shell, causing the user's graphical session to crash and requiring a restart of the desktop environment. Beyond availability issues, there exists a secondary risk related to confidentiality. Depending on how the operating system handles memory allocation for such buffers, reading beyond the allocated space may expose adjacent memory contents. These adjacent regions could contain sensitive data from other applications or system processes, potentially leading to unauthorized information disclosure if an attacker can carefully craft payloads to leak specific memory states.
In terms of threat modeling and industry standards, this vulnerability aligns with MITRE ATT&CK techniques related to initial access and execution through compromised services. An adversary controlling a remote search provider could leverage this flaw as part of a supply chain attack vector or via phishing campaigns that direct users to malicious search endpoints. The exploitation does not require local user interaction beyond initiating a search, making it particularly dangerous in environments where trusted-looking but actually hostile third-party integrations are enabled by default.
Mitigation strategies should focus on both immediate patching and long-term architectural improvements. Users must apply the latest updates provided by their distribution maintainers to ensure they have patched versions of GNOME Shell that include proper bounds checking for D-Bus received data. From a development standpoint, implementing strict validation routines that compare declared image dimensions against actual buffer sizes before processing is essential. Additionally, enabling compiler-based security features such as stack canaries and address space layout randomization can help mitigate the impact of memory corruption errors by making exploitation more difficult. Security teams should also review configurations for remote search providers to ensure only trusted sources are allowed to integrate with the desktop environment's search functionality.